Improved process foe finishing sheet metal



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CHARLES H. PERKINS, OF PROVIDENCE, RHODE ISLAND.

Letters Patent No. 60,781, dated January 1, 1867.

IMPROVED PROCESS FOR FINISHING SHEET METAL.

TO ALL WHOM IT MAY concerns.

Be it known that I, CHARLES H. PERKINS, of the city and county of Providence, in the State of Rhode Island, have invented certain new and useful improvements in the Process for treating Sheet-Iron Plates for the purpose of bluing and finishing them in imitation of Russia iron; and I do hereby declare that the following specification is a full, clear, and exact description thereof.

In the letters patent of the United States, granted to me on the 13th day of February, A. D. 1866 and also" on the 27th day of March, A. D. 1866, certain processes are described for treating sheet-iron plates which are to be manufactured in imitation of Russia. iron. The former of these patents relates to a process'which consists, first, in removing by mechanical means thesuperficial scale of oxide of iron which coats the surface of the sheet-iron plate of commerce; and, second, in subjecting the sheet so cleaned and brightened to the action, while in a close oven, of a degree of heat sufliciently powerful to produce, by partial oxidation, :1. dark blue color. The second patent, before referred to, relates to a process of converting the impure oxide which coats the surface into pure iron, and in this way preparing the sheet for being glazed or blued. The process consists, first, in decarbonizing the plates by subjecting them to the action of heat while enclosed in an air-tight flask, the plates being packed therein and covered entirely, as well as their surfaces, between each pair, with iron chips or filings; second, by subjecting each plate to extreme pressurebetween the surfaces of polished rollers; and, third, in repeating the process of decarbonization and annealing first performed.v

The presentinvention is intended for use'in the manufacture of Russia iron more. particularly in connection with the process described in the second of the above-mentioned. patents, but it. may also be used to blue and finish plates which have been cleaned of scale and brightened by any other process. 7

The invention consists, first, in subjecting the plates to the action of the heat while enclosed in a tight flask, the plates being so arranged within the flask that the surfacesof no two of them shall be in contact, but each plate shall be suspended in a free-air space; second, in subjecting the sheets after the last-named process to the pressure of rollers, or to blows over its entire surface from a hammer or similar instrument. I take a convenient number of plates which have been freed of scale and made ready for bluing, and arrange them in a flask of the proper size to accommodate them. The plates may be set up edgcwise, their ends resting in upright grooves made in the sides of the flask, so that their surfaces shall not touch, or they may be arranged in any other preferred way which will secure their surfaces from contact with each other or with the sides of the flask. The flask, having been closed so as to be air-tight, is then placed in an oven or furnace chamber, and

subjected to a heat of about six hundred degrees for about fourteen hours. The flask is then withdrawn and allowed to cool gradually. The whole time consumed in the operation of heating and cooling will be usually not far from thirty-six hours. Each sheet will, when removed from the flask, be' found to be of an uniform blue color throughout every portion of its surface, but such color will be dead rather thanlustrous. To obtain the bright lustre which distinguishes Russia iron, I next cause each plate to be passed through a pair of polished rollers and subjected to pressure, not suflicient to draw the sheet, but enough only to compress its surface. Instead of subjecting each plate singly to this operation, it is quite as well to take two or more, placed in a pile and pass them through the rollers together. And I have found also that the same result upon the surface is produced by hammering, with a smooth-faced hammer or with a wooden beetle, the entire surface of the plate. This latter operation of subjecting the sheets to the pressure of rollers or the percussionaof hammers imparts to their surfaces a bright and enduring lustre, which in point of appearance and durability is fully equal to the best Russia iron; and, where the process described in the patent granted to me on the twentyseventh day of March, A. D. 1866, is employed for preparing the plates, in connection with the process herein described for bluing and annealing and finishing them, the article produced, when made ofordinary American sheet-iron of suitable quality, is, in quality, pliability, and density, as well as in appearance, in no respect inferior to the best specimens of Russian manufacture. i

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The process herein described of annealing and imparting a blue color to sheet-metal. plates, consisting in subjecting such plates, which have been previously suitably cleansed and brightened, to the action of heat applied while the plates are enclosed in a close flask, the plates being so arranged within the flask that their surfaces shall be surrounded by a free-air space, substantially as set forth.

) 2.- 1 The process herein described of finishing sheet-iron plates by first coloringthe same in the manner above: set forth; ,and, secondly,- in subjecting the plates after being colored to-the action of pressure rollers or.

equivalent means for producing a dense and lustrous surface, substantially as described.

9 CHARLES H. PERKINS.

Witnesses:

Joni: D. Tuunsron, Bans. F. Tmmsron. 

